A facile synthesis of γ-butenolides via cyclization of 3-alkenoic acids with dimethyl sulfoxide and oxalyl bromide

Article abstract of DOI:10.1080/00397911.2019.1652914

The combination of dimethyl sulfoxide and oxalyl bromide was used to accomplish the cyclization of 3-alkenoic acids with the aid of a base to afford γ-butenolides, in which bromodimethylsulfonium salt generated in situ was proposed to serve as a Br⁺ source.

Full text of DOI:10.1080/00397911.2019.1652914

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A facile synthesis of γ-butenolides via cyclization of
3-alkenoic acids with dimethyl sulfoxide and oxalyl
bromide
Rui Ding, Yongguo Liu, Lei Liu, Huimin Li, Sichen Tao, Baoguo Sun & Hongyu
Tian
To cite this article: Rui Ding, Yongguo Liu, Lei Liu, Huimin Li, Sichen Tao, Baoguo Sun & Hongyu
Tian (2019): A facile synthesis of γ-butenolides via cyclization of 3-alkenoic acids with dimethyl
sulfoxide and oxalyl bromide, Synthetic Communications, DOI: 10.1080/00397911.2019.1652914
To link to this article: https://doi.org/10.1080/00397911.2019.1652914
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https://doi.org/10.1080/00397911.2019.1652914
A facile synthesis of c-butenolides via cyclization of 3-
alkenoic acids with dimethyl sulfoxide and oxalyl bromide
Rui Ding, Yongguo Liu, Lei Liu, Huimin Li, Sichen Tao, Baoguo Sun, and
Hongyu Tian
Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Key laboratory of
Flavor Chemistry, Beijing Technology and Business University, Beijing, China
ABSTRACT
ARTICLE HISTORY
The combination of dimethyl sulfoxide and oxalyl bromide was used
to accomplish the cyclization of 3-alkenoic acids with the aid of a
base to afford c-butenolides, in which bromodimethylsulfonium salt
Received 13 June 2019
KEYWORDS
þ
c-Butenolides; 3-alkenoic
acids; cyclization; dimethyl
sulfoxide; oxalyl bromide
generated in situ was proposed to serve as a Br source.
GRAPHICAL ABSTRACT
Introduction
c-Butenolides occur widely in a variety of biologically active molecules as an important
[1]
structural unit, such as flavors, plant growth regulator, cytotoxicity, and antimicrobial.
Many synthetic methods have been developed due to the versatility of this class of com-
[2–7]
pounds.
Some asymmetric approaches for optically active c-butenolides are also avail-
able, such as the Sharpless asymmetric dihydroxylation of 3-alkenoates followed by
[
8,9]
cyclization and elimination,
enantioselective oxidative cyclization of 3-alkenoic acids
[6]
with a chiral electrophilic selenium catalyst, and chemoenzymatic synthesis by transesteri-
fication of 1-alken-3-ols with Novozyme 435 followed by ring-closing metathesis.
[10]
Among these approaches, cyclization of 3-alkenoic acids is a very straightforward way to
afford c-butenolides. 3-Alkenoic acids can undertake intramolecular cyclization reaction
[11,12]
with palladium(II) to give c-butenolides.
Various selenium electrophiles have also
been reported to accomplish cyclization of 3-alkenoic acids to produce unsaturated c-lac-
[
13–16]
tones.
The electroorganic synthesis of c-butenolides from 3-alkenoic acids was
[17]
developed with diselenides as catalysts.
molactonization
c-Butenolides can also be obtained by the bro-
[18,19]
[20–22]
or sulfonyloxylactonization
of 3-alkenoic acids. However, these
CONTACT Hongyu Tian
tianhy@btbu.edu.cn
Beijing Advanced Innovation Center for Food Nutrition and Human
Health, Beijing Key laboratory of Flavor Chemistry, Beijing Technology and Business University, Beijing, China.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lsyc.
Supplemental data for this article can be accessed on the publisher’s website.
ß 2019 Taylor & Francis Group, LLC

2
R. DING ET AL.
Scheme 1. Cyclization of 3-alkenoic acids with DMSO/(COBr)2.
existing methods for cyclization of 3-alkenoic acids usually suffer from certain drawbacks
more or less, such as low yields, long reaction time, or expensive reagents. A convenient
efficient method is still highly desirable for the transformation of 3-alkenoic acids to
c-butenolides.
The combination of dimethyl or diphenyl sulfoxide and oxalyl halide has been found to
[
23]
accomplish various transformation in our recent work, including sulfenyllactonization,
[24]
[25]
[26]
chlorolactonization,
bromination,
dehydration of aldoximes,
sulfenyletherifica-
[
27]
[28]
tion,
acids were observed to be converted to c-butenolides under basic conditions.
those results, we then reported a synthetic method of c-butenolides by reactions of 3-alke-
and sulfenylchlorination.
In our work about chlorolactonization, 3-alkenoic
[
24]
Based on
[
29]
noic acids with diphenyl sulfoxide/oxalyl chloride.
The main disadvantage about this
method is that diphenyl sulfoxide was transformed to diphenyl sulfide, from which the
products had to be separated by column chromatography. It was also found that c-buteno-
lides were produced when 3-alkenoic acids were treated with DMSO/(COBr) under basic
2
[25]
conditions.
We envision that the combination of DMSO/(COBr) should be more suit-
2
able for the synthesis of c-butenolides than Ph SO/(COCl) since the by-product dimethyl
2
2
sulfide derived from DMSO is easy to be removed. Herein, we report a convenient synthe-
sis of c-butenolides via cyclization of 3-alkenoic acids with DMSO/(COBr) (Scheme 1).
2
Results and discussion
A total of thirteen 3-alkenoic acids were investigated in the present work and the results
were shown in Table 1. The typical procedures for cyclization of these 3-alkenoic acids
were as follows. To a solution of oxalyl bromide (1.5 equiv) in CH Cl (10 mL) cooled
2
2
ꢁ
at ꢀ10 C was added dropwise a solution of dimethyl sulfoxide (1.5 equiv) in CH Cl
2
2
under the atmosphere of nitrogen. After 10 min, a solution of 3-alkenoic acid (1.0
equiv) in CH Cl was added. The mixture was then allowed to warm up to room tem-
2
2
ꢁ
perature and stirred for 1 h. Distilled water was added dropwise at 0 C. After stirring
for 10 min, a base (5.0 equiv) was added and stirred for 5–6 h. The corresponding
c-butenolides were obtained after a routine workup.
All the 3-alkenoic acids with 4-alkyl groups afforded the corresponding c-2-buteno-
lides in excellent yields (entries 1–10). For 3-butenoic acid 1, K CO was added to pro-
2
3
mote the cyclization and elimination to give c-2-butenolide 14 in 92% yield (entry 1).
The cyclization and elimination were completed in 6 h. For the other 3-alkenoic acids
2–10, it usually took more than 12 h to complete the cyclization and elimination in the
presence of K CO . If NaOH was used instead, the reactions were accomplished in
2
3
about 5 h. The reactions of 3-alkenoic acids 1–7 afforded c-2-butenolides 14–20 with
high purity after workup without further purification (entries 1–7), whereas the crude
products for 3-alkenoic acids 8–10 were not very pure and needed to be purified on
column chromatography (entries 8–10).
Three 3-alkenoic acids with 4-aryl groups were also investigated (entries 11–13). 4-
Phenyl-3-pentenoic acid 11 was converted to the corresponding c-2-butenolide 24 in

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SYNTHETIC COMMUNICATIONS
3
a
Table 1. Cyclization of 3-alkenoic acids with DMSO/(COBr) .
2
b
Entry
Substrate
Product
Yield
92%
1
c
1
14
2
3
4
5
6
7
93%
93%
95%
94%
92%
91%
d
2
15
d
3
16
d
4
17
d
5
18
d
6
19
7
d
2
2
0
8
9
89%
8
d
1
85%
90%
87%
d
9
2
2
1
0
1
d
1
0
23
1
c
2
4
1
1
e
1
1
2
3
78%
c
1
2
25
77%
1
3
c
2
6
a
ꢁ
All reactions were carried out in CH
acid (1.0 equiv.), DMSO (1.5 equiv.) and (COBr)
2
Cl
2
at ꢀ10 C to room temperature using 3-alkenoic
2
(1.5 equiv.). After completion of the reac-
tion, 5.0 equiv. of base was added in the following workup.
Isolated yield after column chromatographic purification.
b
c
K
2
CO
3
was used as a base in workup.
d
e
NaOH as a base in workup.
The product contained about 17% c-3-butenolide.

4
R. DING ET AL.
Scheme 2. The formation pathway of c-butenolides from 3-alkenoic acids with DMSO/(COBr)2.
8
7% yield (entry 11). 4-Phenyl-3-butenoic acid 12 gave a mixture of 4-phenyl-c-2-bute-
nolide 25 and 4-phenyl-c-3-butenolide with a ratio of 5: 1 in a combined yield of 78%
entry 12). For 4-p-bromophenyl-3-butenoic acid 13, 4-p-bromophenyl-c-3-butenolide
6 was obtained in 77% yield (entry 13). For these 4-aryl substituted 3-alkenoic acids,
K CO was used to accomplish the elimination in about 5 h. In contrast, the reaction
(
2
2
3
systems became complex in the presence of NaOH.
The pathway of transformation of 3-alkenoic acids to c-butenolides by treatment with
DMSO/(COBr) was proposed as follows (Scheme 2). DMSO reacted with (COBr) to
2
2
þ
generate bromodimethylsulfonium salt, which served as a source of Br . The bromodi-
methylsulfonium salt undertook an electrophilic addition to the double bonds of 3-alke-
noic acids to produce a cyclic bromonium ion, which could be converted to a
dibromide or bromolactone. As we mentioned in our previous work about bromination
[
25]
of alkenes,
the dibromides were formed as major products for the 3-alkenoic acids
with 4-alkyl groups; whereas the 3-alkenoic acids with 4-aryl groups produced the cor-
responding bromolactones. The intermediate dibromide was then treated with a base to
form a bromolactone, which was easy to undergo an elimination to afford the corre-
sponding c-butenolide. For the substrates 1–11, an a proton of carbonyl group was
removed in the elimination step to generate a c-2-butenolide (entries 1–11). In contrast,
for the substrates 12 and 13, the proton attached to the C4 with a phenyl group could
also be removed, which led to c-3-butenolides with a double bond conjugated to a phe-
nyl group (entries 12 and 13). The substrate 12 still gave the c-2-butenolide 25 as the
major product, but the substrate 13 only produced the c-3-butenolide 26.
Most of the substrates have been investigated in our previous method using Ph SO/
2
[29]
(COCl)2
except the substrates 3 and 5. In comparison, this present method with DMSO/
(
COBr) usually demonstrated a clean conversion with higher yields. c-Butenolides products
2

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SYNTHETIC COMMUNICATIONS
5
were able to be obtained with high purity without further purification after a usual workup
in some cases. Since the by-product dimethyl sulfide was easy to be removed, this simplified
the purification procedure greatly. Meanwhile, compared with the existing approaches for
[11–22]
cyclization of 3-alkenoic acids,
this method also presents remarkable advantages, such
as easy accessibility of reagents, relatively short reaction time, high yields and sim-
ple operation.
Conclusion
In summary, c-butenolides can be prepared by cyclization of 3-alkenoic acids with the
combination of DMSO/(COBr) , which presents prominent advantages over the existing
2
methods. It provides a highly efficient way for the preparation of c-butenolides from 3-
alkenoic acids.
Experimental
1
NMR spectra were obtained on a Bruker AV 300 spectrometer ( H NMR at 300 MHz,
1
3
C NMR at 75 MHz) in CDCl using TMS as an internal standard. Chemical shifts (d)
3
were given in ppm and coupling constants (J) in Hz. TLC was performed with pre-
coated TLC plates, silica gel 60 F-254, layer thickness 0.25 mm. Flash chromatography
separations were performed on 100–200 mesh silica gel. Reagents and solvents are com-
mercial grade and were used as supplied. Substrates 1–7 and 12 are commercially avail-
able and were purchased from Innochem; the other five 3-alkenoic acids (8–11 and 13)
were synthesized in our lab.
General procedure for synthesis of butenolides using DMSO and (COBr)2
To a solution of oxalyl bromide (1.07 mL, 7.5 mmol, 1.5 equiv) in CH Cl (10 mL)
2
2
ꢁ
cooled at ꢀ10 C was added dropwise a solution of dimethyl sulfoxide (0.53 mL,
7.5 mmol, 1.5 equiv) in CH Cl (10 mL) under the atmosphere of nitrogen. After
2 2
1
0 min, a solution of 3-alkenoic acid (5 mmol, 1.0 equiv) in CH Cl (10 mL) was added.
2
2
The mixture was then allowed to warm up to room temperature and stirred for 1 h.
ꢁ
Distilled water (20 mL) was added dropwise at 0 C. After stirring for 10 min, NaOH
(
1.00 g, 25 mmol, 5.0 equiv) or K CO (3.45 g, 25 mmol, 5.0 equiv) was added and
2 3
stirred for 5 h. The organic layer was separated and successively washed with brine
2 ꢂ 30 mL). The combined organic extracts were dried (Na SO ), filtered, and concen-
(
2
4
trated in vacuum to afford the corresponding a,b-unsaturated-c-lactones. The products
4–20 can be obtained in high purity without further purification, the products 21–26
1
need purification by flash chromatography (silica gel, PE/EtOAc ¼ 9:1).
Furan-2(5H)-one (14)
1
Colorless oil, 387 mg, 92% yield. H NMR (300 MHz, CDCl ) d 7.58 (dt, J ¼ 5.7, 1.5 Hz,
3
13
1
H, H–C-4), 6.18 – 6.15 (m, 1 H, H–C-3), 4.90 (t, J ¼ 1.8 Hz, 2 H, H–C-5). C NMR
(
75 MHz, CDCl ) d 173.79 (C-2), 153.07 (C-4), 121.51 (C-3), 72.23 (C-5).
3

6
R. DING ET AL.
5
-(4-Bromophenyl)furan-2(3H)-one (26)
1
White solid, 916 mg, 77% yield. H NMR (300 MHz, CDCl ) d 7.56–7.52 (m, 2 H, H-
3
C3-phenyl and H-C5-phenyl), 7.49–7.45 (m, 2 H, H–C2-phenyl and H–C6-phenyl), 5.81
13
(
t, J ¼ 2.7 Hz, 1 H, H–C-4), 3.41 (d, J ¼ 2.7 Hz, 2 H, H–C-3). C NMR (75 MHz, CDCl3)
d 175.58 (C-2), 153.24 (C-5), 132.09 (C3-phenyl and C5-phenyl), 127.43 (C1-phenyl),
26.40 (C2-phenyl and C6-phenyl), 123.92 (C4-phenyl), 98.46 (C-4), 34.83 (C-3).
1
Funding
Financial support from the National key research and development program (2016YFD0400801),
Beijing Postdoctoral Research Foundation [2017-22-011].
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